目前，大約有30%的膝關(guān)節(jié)置換手術(shù)，會(huì)因?yàn)殡y以對(duì)骨骼內(nèi)部進(jìn)行精確定位而產(chǎn)生錯(cuò)位問題。不過，現(xiàn)在已經(jīng)能在手術(shù)前，透過亞德諾(ADI)公司的高精度微機(jī)電系統(tǒng)(MEMS)傳感器，迅速追蹤病人的膝關(guān)節(jié)定位(alignment)和運(yùn)動(dòng)狀況。一家位于加州的 OrthAllign 公司，正在努力將膝關(guān)節(jié)定位的成功率提高到100%。
“ADI的高精度慣性測(cè)量單元(IMU)，讓我們的Knee Align系統(tǒng)可執(zhí)行平均要價(jià)40萬(wàn)美元甚至更高價(jià)光學(xué)系統(tǒng)的功能，”O(jiān)rthAlign公司企業(yè)發(fā)展副總裁Darius Kharabi說(shuō)?！艾F(xiàn)在，外科醫(yī)生能運(yùn)用成本更低廉、更易于使用的設(shè)備，在手術(shù)中達(dá)到近乎完美的定位效果?！?
這個(gè)市場(chǎng)非常大，因?yàn)閮H在美國(guó)，每年施行的膝關(guān)節(jié)置換手術(shù)便高達(dá)67.5萬(wàn)例，而據(jù)美國(guó)醫(yī)療照護(hù)研究及品質(zhì)機(jī)構(gòu)(Agency for Healthcare Research and Quality, AHRQ)預(yù)估，到2030年，全美國(guó)將有超過350萬(wàn)人可能要施行膝關(guān)節(jié)置換手術(shù)。
不幸的是，Arthroplasty期刊資料顯示，今天大多數(shù)的膝關(guān)節(jié)置換手術(shù)都使用老舊的機(jī)械式定位工具，由于這些工具的精確度不高，因此定位成功率平均在70%以下。目前部份醫(yī)院采購(gòu)了光學(xué)式定位系統(tǒng)來(lái)增加定位成功率。然而這種儀器非常龐大，難以使用而且昂貴，因而僅有不到5%的外科醫(yī)生在實(shí)施膝關(guān)節(jié)置換手術(shù)時(shí)會(huì)使用到它。
OrthAlign的醫(yī)療儀器使用了ADI包含三軸陀螺儀和加速器的慣性測(cè)量單元(IMU)，
能在膝關(guān)節(jié)置換手術(shù)中引導(dǎo)外科醫(yī)生的手術(shù)刀。C5lesmc
另一方面，采用MEMS技術(shù)的全新OthAllign設(shè)備，其尺寸精巧到足以用手握住，而且便宜到能夠一次性使用后便丟棄，使用它的時(shí)間只需要幾秒鐘，但其精確度卻足以媲美高達(dá)數(shù)十萬(wàn)美元甚至更高價(jià)的光學(xué)設(shè)備，OthAllign公司表示。
OthAllign成立于2008年，已開發(fā)并展示一套基于MEMS的膝關(guān)節(jié)手后定位系統(tǒng)，用于全膝關(guān)節(jié)置關(guān)手術(shù)(total knee arthroplasty, TKA)之中。該公司表示，其第二代KneeAlign儀器已獲得美國(guó)FDA核準(zhǔn)，在TKA手術(shù)中，當(dāng)必須對(duì)膝關(guān)節(jié)的上下部位進(jìn)行切除以置換成新的人工關(guān)節(jié)時(shí)，這套儀器可更良好地引導(dǎo)外科醫(yī)生。
OrthAllign表示，選擇ADI IMU是由于該組件內(nèi)含高精度的三軸陀螺儀及加速器，能實(shí)時(shí)追蹤膝蓋的定位情況。在將一個(gè)IMU-bearing模塊附加在膝關(guān)節(jié)上之后，外科醫(yī)生只需要在一般的移動(dòng)范圍內(nèi)移動(dòng)膝蓋──過程不用到一分鐘──在這個(gè)MEMS傳感器使用精確運(yùn)動(dòng)追蹤資料的算法計(jì)算后，便可精確得知必須從骨頭的何處下刀。該公司的KneeAlign儀器前端附有一個(gè)顯示器，可為外科醫(yī)生顯示如何精確調(diào)整其切割儀器，以確保要換上的人造關(guān)節(jié)能精確定位。
OrthAllign基于MEMS的KneeAlign儀器已經(jīng)被用在紐約的Hospital for Special Surgery，以及圣地亞哥的Scripps Green Hospital之中，預(yù)計(jì)2012年第一季能廣泛供應(yīng)給全美各地的醫(yī)院。
編譯： Joy Teng
本文授權(quán)編譯自EE Times，版權(quán)所有，謝絕轉(zhuǎn)載
參考英文原文：：Medical MEMS tackles knee replacement，by R. Colin Johnson
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Medical MEMS tackles knee replacement
R. Colin Johnson
PORTLAND, Ore.—Currently, more than 30 percent of knee replacement surgeries suffer from misalignment problems caused by the "fog of surgery"–where the precise orientation of internal bones is difficult to determine. By adding a complement of Analog Device Inc.'s high-precision MEMS sensors to track the alignment and motion of a patient's knee during the surgery, OrthAlign Inc. (Aliso Viejo,Calif.) aims to dramatically increase precision.
"The high-precision of Analog Devices' IMU enables our KneeAlign system to perform as well as optical systems that cost $400,000 or more," said Darius Kharabi, OrthAlign’s vice president of corporate development. "Now surgeons can now get a much higher degree of precision with an easy-to-use device that costs a fraction of the price."
The stakes are huge, since more than 675,000 knee replacements are performed every year in the U.S. alone, with trends indicating that as many as 3.5 million Americans will have the procedure performed by 2030, according to the Agency for Healthcare Research and Quality (Rockville, Md.).
Unfortunately, today most knee replacements are performed using antiquated mechanical alignment tools which are imprecise, resulting in a success rate of less than 70 percent, according to according to studies in the Journal of Arthroplasty (Mason, 2007) . Until now, the only alternative was purchasing an optical alignment system to increase success rates. But the instruments are bulky, hard-to-use and expensive, resulting in less than 5 percent of knee procedures performed using them.
The new OthAllign MEMS-based instrument, on the other hand, is small enough to hand hold, cheap enough to throw away after a single use, works in just a few seconds, and is as precise as the optical systems costing hundreds of thousands of dollars more, according to OrthAlign.
OrthAlign was founded in 2008 and has already demonstrated a MEMS-based knee-surgery alignment tool for performing one part of the total knee arthroplasty (TKA) procedure. The company received Food and Drug Administration clearance earlier this year for its second-generation KneeAlign instrument, which guides the surgeon when making both the top and bottom severances necessary to remove the natural knee and insert the mechanical one during TKA.
The IMU from Analog Devices was chosen for its high-precision use of three-axis gyroscopes and accelerometers to track knee orientation in real time, according to OrthAlign. After attaching the IMU-bearing module to the natural knee, the surgeon merely moves the natural knee threw its normal range of motion—a procedure that takes less than 30 seconds—after which algorithms uses the precision motion tracking data from the MEMS sensors to calculate the positioning of the cutting instrumentation on the knee. A display on the front panel of the KneeAlign instrument shows surgeons the real-time positioning of their cutting instrument to help ensure precise alignment for the artificial knee.
OrthAlign's MEMS-based KneeAlign instrument is currently being used by the Hospital for Special Surgery (New York) and the Scripps Green Hospital (San Diego), but will be available to hospitals in select geographies in the first quarter of 2012.
